Discovery May Lead to Earlier Diagnosis for Breast Cancer

A new study identifies a gene that may help doctors diagnose breast cancer. (Wikimedia Commons)

Doctors and patients know the earlier someone gets a cancer diagnosis, the better the chance that treatment will work. So anything that helps catch cancer at an earlier stage could help save lives.

Most cancers happen because of mistakes or mutations in the DNA of key genes. When any key gene is damaged, the chances the cell will grow uncontrollably go up. And cells growing uncontrollably is the very definition of cancer.

Most women are not born with a mutation in this gene. Instead, over a lifetime, they develop the mutations in their breast cells that can induce tumors.

The researchers looked at 249 breast cancer samples and found that in more than 70 percent of them, a gene that is normally turned off in adults has mutated and turned on. And because the mutated gene is harder to detect in some of the later stage cancers the researchers looked at, it could be even more common than this.

The identified gene, GT198, has been associated with breast and ovarian cancer in the past but it is in this study where the researchers determined at least one way the mutated gene can cause a tumor to grow.

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When GT198 is mutated, it can turn on other genes that encourage tumor growth.

How Might This Change Diagnosis or Treatment?

This finding suggests that doctors who find something suspicious in a breast exam could look for signs of a mutated GT198. The doctor would remove some tissue from the breast to see if the GT198 gene is on in a set of cells called stromal cells. If it is, a red flag would go up and the doctor could do some additional testing in order to discern whether there's a young tumor, leading to early treatment that could perhaps nip the breast cancer in the bud.

If the results hold up, a diagnostic test to find out whether the gene has mutated should be pretty straightforward to design.

In the more distant future, scientists may design new treatments based on this mutated gene. For example, they might look for how to goose a patient’s immune system to attack only the cells where the gene is turned on. If we had immunotherapy that killed only cancer cells, there might be fewer side effects than with current treatments like radiation and chemotherapy.

Another avenue for treatment based on this work would be to go after the protein that the GT198 gene helps build. As is usually the case, it is the protein and not the gene itself that is doing the dirty work and causing the cancer. So perhaps researchers could find some small molecule that stops the protein from turning on tumor-encouraging genes. Ideally, this would at least slow down tumor growth.

The results will need to be confirmed at least in part by analyzing additional breast cancer samples. If the results hold up, then the diagnostic test to find out whether GT198 is turned on should be pretty straightforward to design. Treatments based on these findings would not be. They may not be available for quite a while.

Inherited or Spontaneous

Cancer happens when key genes are damaged. The DNA can be damaged from things in the environment like cigarette smoke or the ultraviolet light from the sun, or a cell can simply make a mistake when copying its DNA.

Most cancers happen when key DNA is damaged or is copied incorrectly. (Wikimedia Commons)

Some people inherit mutated genes that make it more likely they'll develop cancer. BRCA1, the gene made famous by Angelina Jolie, is one of these. She inherited a mutated BRCA1 gene that raised her risk of developing breast (and ovarian) cancer later in life.

The authors of this study estimated from previous work that 4% of breast cancers that run in the family may have the mutated GT198 gene. But in the study, more than 70 percent of the breast cancers had a mutated GT198 gene, so it's clear many women had not inherited the mutation.

It turns out most women are not born with a mutated GT198 gene, but develop mutations in this gene in their breast cells over their lifetime.

This is how the vast majority of cancers develop. Mutations happen in our DNA as we live our lives.

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Still, researchers are working on a genetic test that looks for people born with a mutated GT198 gene. Like the test for mutant BRCA1/2 genes, it would help people find out if they're at a higher risk for developing breast cancer.